Catalytic cracking of dewaxed petroleum hydrocarbons



Aug. 25, 1953 HARESNAPE ETAL 2,650,189

N. CATALYTIC CRACKING OF DEWAXED PETROLEUM HYDROCARBONS Filed March 1, 1949 2 Sheets-Sheet 1 ML 76W --A MFF/AMTE zxmww Coll/MN Inventors: John Norman Haresnape Ernest$lton Hous%h y= At rneirs:

.duction of anaromatic Patented Aug. 25, 1953 OFFICE 2,650,189 CATALYTIC CRACKING 0F DEWAXED PETROLEUM John Norman Haresna HYDROCARBONS pe and Ernest Carlton" Housam, Sunbury-on-Thames, England, assignors to Anglo-Iranian Oil Company Limited, London, England, a British joint-stock corpo-.

ration Application March 1, 1949, Serial No. In Great Britain March 2, 1948 2 Claims.

The invention relates to the catalytic cracking of petroleum hydrocarbons.

It is known to subject the higher-boiling fractions from petroleum to catalytic cracking for the production of gasoline and gas oil. If the feedstock contains sulphur, the cracked products will also contain sulphur which must beremoved in a refining treatment when a high quality gasoline of low sulphur content is required. It is also known to recycle the fraction boiling above the gas oil range to the cracking zone, but it has been found that this recycled fraction is highly refractory.

It is an object of the present invention to enable products of increased octane number and of reduced sulphur content to be obtained from sulphur-containing feedstocks. It is also an object of the invention to reduce the amount of the fraction boiling above the gas oil range while increasing its susceptibility to cracking.

According to the process of the invention, a high-boiling petroleum fraction is treated with a solvent for aromatic hydrocarbons for the proextract and a rafiinate, and the raflinate subjected According to a further feature of the inven-- tion, where the rafiinate contains wax, the waxy raflinate may be dewaxed for the production of wax and a dewaxed raflinate, either or both of which may be subject to catalytic cracking. The dewaxing operation is effectively carried out by means of a solvent such as, for example, a mixture of acetone, benzene and toluene.

The aromatic extracts recovered in carrying out the process of the invention are useful as fuel oil components, and in certain cases, as plasticisers.

In the accompanying drawings:

Figure 1 illustrates the manner of carrying out the solvent extraction step, and

Figure 2 is a diagrammatic representation of the example hereinafter described.

Referring first to Figure 1, molten phenol contained in vessel A is pumped by the pump P, into the top of the extraction column D down which it flows countercurrent to a rising stream of wax distillate pumped by the pump P2 from the vessel B into the base of the column, the phenol being 80% by volume of the wax distillate. The temperatures at the top and bottom of the column are 130. F. and 110 F. respectively. Water (5% by volume on the phenol) is injected from the vessel C by the pump P3 into the extract phase settler S to assist separation of the phases. The raflinate and extract phases are withdrawn from to catalytic cracking.

Iranian wax distillate the top and bottom of the column through lines E and F respectively at such a rate that the interface I between the phases remains stationary, and each phase is passed to a striping system for removal of the phenol in known manner for reuse, the extract phase by means of pump P4.

In the dewaxing stage, the rafiinate is mixed with 400% by volume of a solvent consisting of acetone, benzene and toluene in the proportions by volume of 28:40:32 cooled to 20 F. and the separated wax filtered on at this temperature.

The invention will now be described by way of example with reference to the treatment of having a specific gravity at 160 F. of 0.871 and a sulphur content of 1.5% weight.

The wax distillate for the production of waxy raflinate.

was extracted with phenol an aromatic extractand a The waxy rafiinatewas then production of a dewaxedraffinate The yields of the various fractions and their proportions are set out in the following Table I.

Table I Y; 1d" 1t Sul h Fraction i s. o.@ P

Material Vol. (Rams), wt. Percent 16001? wt. Percent Percent 1) Extract 26.1 0. 0745 0. 07 3.65 2 Rafiinate 73.0 0. 8345 0.20 3) Dewaxed rai- 50.1 0.8475 0.. 21 0.80

finate. (4) Wax 14.8 0.786

Feedstock. 100. 0 0. 871 0. 33 l. 5 N

The fractions (2), (3) and (4) were separately cracked over a synthetic silica-alumina catalyst at a temperature of 950 F., and at a space velocity of 0.9 v./v./hr. with a 2-hour process period. The approximate yields of the various products, given on a no-loss basis, are set out in the following Table II.

Table II From a consideration of Table II it is clear that the conversion obtained in cracking any of the fractions (2), (3) and (4) was greater than when cracking the whole wax distillate, and it is particularly-noticeable that the material boiling above the gas oil range was much reduced, which is believed to be due to the removal in the extract of the most highly refractory constitu ents of the wax distillate. Furthermore, the fraction boiling above the gas oil range is in itself more susceptible to cracking. It will also be observed that when cracking the raffinates, the gas/gasoline ratio (by weight) was reduced'as compared with the cracking of the whole distil-' late.

From a consideration of Table I and Table II together, it is clear that the yield of gasoline based on the feedstock is greater when cracking the waxy raifinate than when cracking the Whole distillate.

Inspection data on the gasoline and gas oils produced from the Whole wax distillate and from the fractions (2), (3) and (4) are set out in the following Table III. 1 7

Table III Fraction Feed Raffi- Dewaxed Wax V nate Baffinate Gasolineszg S. G. 60 F 0.7570 7355 0.745 0.7095 Distillationz l V01. to 70 C 17. 5 33.5 29 51 Vol. to 100C 40. 5 54. 5 51 71. 5 Vol. to 140 C 64 73 71. 5 83. 5 Sulphur, wt. percent 0. 108 0.033 0. 043 0. 012 BromineNo. 68 75 66 101 Aniline Pt. 0;; 20 22. 2 21. 5 25. 7 Aromatics, wt. percent, 37 32 7 33. 9 25. 1 Octane Number (Motor Method) 78 80. 9 79. 2 81. 7 Gas Oils:

S. G. 60 F i 0.946 0.930 0.939 0.877 Sulphur, wt. percent; 1. 82 1. 10 1. 10 0. 2-0. 32 Pour Pt; F 0 30 -25 10 Aniline Pt., C 16. 0 5 13. 6 38. 0 Diesel Index 11 8 11 30 It will be observed that the gasoline obtained from any of the fractions (2), (3) or (4) has a higher octane number than that obtained from the whole distillate and that the gasoline produced from the rafilnates has a lower volatility to 100 C. than that produced from the Wax, while the sulphur content shows a marked reduction in the case of the raffinates and the wax. Although the gasoline having the highest octane number was produced from the Wax, an almost equal improvement in octane rating was obtained inthe gasoline produced from the waxy raffinate, the yield of which from the wax distillate was about five times that of wax.

The yields of the various fractions obtained by catalytically cracking the whole wax distillate, the raflinate, the dewaxed rafiinate, and the wax respectively are set out in diagrammatic form inFigure 2 of the accompanying drawings which is self-explanatory.

We claim:

1. A catalytic cracking process for the recovcry of a gasoline fraction from a wax distillate comprising treating a wax distillate with asolvent for aromatic hydrocarbons, separating an aromatic extract and a waxy raffinate from the treated distillate,.treating the Waxy raffinate with a dewaxing solvent, separating wax and a dewaxed .rafiinate, subjecting the dewaxed raffinate to catalytic cracking and fractionating the cracked products as such for the recovery of a gasoline fraction. 1 V

2. A process in accordance with claim 1 Wherein the solvent for aromatic hydrocarbons is phenol and the dewaxing solvent consists of a mixture of acetone, benzene, and toluene] J OI-IN NORMAN HARESNAPE.

ERNEST CARLTON HOUSAM.

References Cited ihthefile of this patent UNITED STATES PATENTS Number Name Date 2,020,066 Kiser Nov. 5, 1935 2,054,052 Govers Sept. '8, 1936 2,279,550 Benedict et a1. Apr. 14, 1942 2,397,329 Ruthrufi Mar. 26, 1946 

1. A CATALYTIC CRACKING PROCESS FOR THE RECOVERY OF A GASOLINE FRACTION FROM A WAX DISTILLATE COMPRISING TREATING A WAX DISTILLATE WITH A SOLVENT FOR AROMATIC HYDROCARBONS, SEPARATING AN AROMATIC EXTRACT AND A WAXY RAFFLINATE FROM THE TREATED DISTILLATE, TREATING THE WAXY RAFFINATE WITH A DEWAXING SOLVENT, SEPARATING WAX AND A DEWAXED RAFFINATE, SUBJECTING THE DEWAXED RAFFINATE TO CATALYTIC CRACKING AND FRACTINATING THE 